Investigators have said there were several people in the black Range Rover SUV when the shots rang out.

So far, they have only identified Harris and Ms Howard.

Colleagues of the taxi driver have posted a $35,000 (£23,000) reward for information leading to the arrest of Harris, 26.

Image Caption:The black Range Rover thought to have been used in the shooting

"We lost one of our own in cab driver Michael Boldon," said Brent Bell, president of the Whittlesea Bell Corporation cab company and a member of a trust fund established to pay the reward.

Mr Boldon, 62, was a family man who moved from Michigan to Las Vegas. Passenger Sandra Sutton-Wasmund was a 48-year-old mother of three children who was in town attending a trade show.

Harris has been the subject of a multi-state manhunt since the incident, and police say he has a long criminal history that includes arrests for robbery, sexual assault, kidnapping and soliciting prostitution.

The shootout was the latest in a series of high-profile episodes of violence in Las Vegas.